1. Those having a detailed and first-hand knowledge of Descartes’s work seem agreed that it was highly original, genuinely critical and of permanent importance in the history of thought. And though they would differ in opinion on what are the reasons best advanced in support of their estimate, a majority would seem to regard the “Cartesian revolution” as summing up what is most meritorious in Descartes’s philosophy and most lasting in his influence. They would find Professor E. Gilson speaking their mind when he declares, “Sur ce qu’il y a de nouveau et de strictement original dans sa pensée, aucun doute ne saurait subsister. Descartes est la revendication personnifiée du mathématisme universel.